DE102006002032A1 - A photosensitive coating for enhancing a contrast of a photolithographic exposure - Google Patents

Abstract

A photosensitive coating material for use as a contrast enhancing coating (16, "BCEL") disposed beneath a lacquer film (14) comprises: a base polymer having no acid-cleavable groups so as to be insoluble in a developer, the developer being therefor is designed to remove exposed sections (34) of the paint film (14). A solvent is used to apply the photosensitive coating material to a surface of a substrate (10) or a layer (12) arranged thereon. In one embodiment of the invention, the coating (16) further comprises a photolytic acid generator which is designed such that it releases an acid upon exposure which diffuses into the adjacent lacquer film (14) deposited on the coating (16) to increase an acid concentration formed in exposed portions of the lacquer. In a further embodiment, the coating (16) comprises an alkaline additive which is designed such that it can be photo-decomposed into a non-alkaline, neutral compound upon exposure. This alkaline additive is such that it diffuses into the adjacent paint film (14) above the coating (16). An acid concentration formed in unexposed or less exposed sections (34) of the paint film (14) is thus reduced.

Description

The The invention relates to a photosensitive coating for reinforcing a Contrasts a photolithographic exposure of a on a substrate trained paint. The invention further relates to multilayered Lacquers and / or antireflective coatings.

On The field of semiconductor manufacturing becomes integrated circuits formed by semiconductor wafer layer by layer, each with a pattern be formed, with the corresponding patterns on each Masks are formed of a circuit associated with the set. The wafers are covered with a photosensitive varnish which is applied to the layer to be exposed. With progressive Reduction of the sizes of Structures use special lithographic techniques about the resolution and depth of field in terms of an exposure increase. These techniques relate to improvements, inter alia, to the optical Systems (exposure device), the types of masks (phase shift masks, Trim masks, etc.) or the paints.

One Effect that often occurs when structural elements on a wafer with a width near the resolution limit of the projection optical system is the formation from so-called side praise. These become close to a respective main structure formed in the paint on the substrate. These side praises can become as intensity secondary maxima near the outer surface of a Forming paints on a wafer, as the intensity decreases vertically with the depth and the sub-maxima are unable to set a threshold level for effective Exposure at greater depths to exceed in the paint.

Side Praise can but also as dark artifacts (intensity minima) on the lower surface of a Lacks arise. You will then be near an underlying layer or coating formed in the paint on the wafer. For example can be the projection of a pattern of dark lines through represents absorbent layers on an otherwise light mask are in a deposited on a wafer positive paint too the training of less exposed areas within one Lead the area, but that should be effectively exposed. This is especially true when the projection is defocused.

The same problem occurs with auxiliary structures (SRAF - subresolution assist features) on, to a respective parent structure within such areas added to the mask become. They are supposed to be the process window by an improved contrast and as a result increase a steeper paint profile. At the Bottom of the varnish, however, may become insufficient in intensity the photolytic acid generators in the paint to release acid while to stimulate the exposure. This can lead to after-development Paint residues on the lower surface stay behind and thus to erroneous etching results in terms of the underlying layer lead, the namely subsequently should be structured.

One approach is a reactive ion etching using oxygen as a reactive agent. Hereby, a defined amount (thickness) of developed varnish including the Remains of the wafer surface taken away so that even the unwanted leftovers on the underlying Layer are removed. The paint thickness, however, becomes disadvantageous reduced and the quality the paint profile, especially the paint edges, may deteriorate.

One Another approach is to use structural elements of a floor anti-reflection coating (BARC - bottom antireflective coating). A BARC is often added used to improve exposure properties of a paint, what in particular a reduction of standing waves within the paint due to reflections of light on the lower surface.

There but ammonia, which consists of a nitrogen-containing underlying layer can escape, possibly but the BARC might pervade itself but the adhesion of the paint or sections thereof on the BARC below circumstances significantly enlarge. Around To reduce this liability again, an acid is added to the BARC. There is a side effect in that this acid may be while a heating step after exposure in the adjacent paint diffuses, causing the solubility of the paint during of a subsequent development step. On the present Problem applied, will be the appearance of dark side praise or exposed SRAFs due to the increased amount of acid in a soil area of the paint implicitly reduced.

Examples for ground antireflective coatings (BARC) are described in Meador et al. "Improved Corsslinkable Polymeric Binders for 193 nm Bottom Antireflective Coatings (BARCs) ", in: Advances in Resist Technology and Processing XVIII, Proceedings of SPIE, Vol. 4345 (2001), pages 846-854, or in Devadoss et al., Investigation of BARC-Resist Interfacial Interactions ", in: Optical Microlithography XVI Proceedings of SPIE, Vol. 5040 (2003), pages 912-922.

Another approach is to use developable BARCs. Your goal is the cons the homogeneous dry etching process to remove the paint residues by the BARC is made soluble in a developer, for example, just that developer, which is applied to the paint. Accordingly, exposed areas of the paint are removed simultaneously with those portions of the BARC that are adjacent to the exposed areas as the developer solution progresses through the paint BARC interface. However, so-called under-cutting effects may occur due to the isotropic development behavior when portions under unexposed areas of the paint are dissolved by the developer. In addition, the development contrast of those BARCs may possibly be limited, so that only a minimum width of the structural elements (lines) of, for example, 180 nm can be achieved using such BARCs.

Examples for developable BARCs are described in Cox et al., Developer Soluble Organic BARCs for KrF Lithography ", in: Advances in Resist Technology and Processing, Proceedings of SPIE, Vol. 5039 (2003), pages 878-882, or in Krishnamurty et al., "Novel Spin Bowl Compatible, Wet Developable Bottom Anti-Reflective Coating for I-Line Applications ", in: Advances in Resist Technology and Processing, Proceedings of SPIE, Vol. 5039 (2003), pages 883-890.

One busy approach with light-sensitive or light-definable BARCs. A photolytic acid generator (PAG) is added to the BARC to give a Release acid. The resin of the BARC has acid cleavable Groups on. This type of developable BARC then includes features a typical, chemically amplified Lacks (CAR - chemically amplified resist). In particular, the profile of the developed Anisotropic lacquers because only exposed areas within the BARC in terms of a developer applied to the paint are soluble.

Photosensitive or light-definable BARCs are described, for example, in Owe-Yang et al., "Application of Photosensitive BARC and KrF Resist on Implant Layers ", in: Advances in Resist Technology and Processing, Proceedings of SPIE, Vol. 5376 (2004), pages 452-459, or in Guerrero et al., "A New Generation of Bottom Anti-Reflective Coatings (BARCs): Photodefinable BARCs ", in: Advances in Resist Technology and Processing, Proceedings of SPIE, Vol. 5039 (2003), pages 129-134.

A The object of the invention is thus to improve the quality of lithographic projection, in particular dense periodic or semi-dense lines of a mask in a deposited on a wafer paint. Another Task is to improve the during an exposure, a subsequent hardening and a development in a paint achievable contrast. A Another task is to reduce the occurrence of dark Side praise within areas to be exposed at or near the bottom interfaces (Floor areas) of a paint. Another task is the Improvement of the resolution and the depth of field in terms of a photolithographic exposure.

The Task is solved by a photosensitive coating material having the features according to claim 1. The object is further solved by a photosensitive Coating material having the features according to independent claim 21. Advantageous Embodiments are each dependent on the dependent claims remove.

• – eine Kontrastverstärkungsschicht (BCEL – contrast enhancing layer), die aus einem der vorgeschlagenen lichtempfindlichen Beschichtungsmaterial besteht, d.h. mit einem fotozerlegbaren alkalischen Additiv und/oder einem fotolytischen Säuregenerator und mit einem Basispolymer, das keine säurespaltbaren Gruppen aufweist, wobei die Kontrastverstärkungsschicht auf dem Substrat abgeschieden wird; und
• – mindestens einen lichtempfindlichen Lackfilm, der auf der Kontrastverstärkungsschicht angeordnet ist, so dass die Kontrastverstärkungsschicht (BCEL) den lichtempfindlichen Lackfilm an dessen Lackbodenfläche kontaktiert, also unterhalb der des Lackfilms angeordnet ist.

Further aspects of the invention relate to the provision of a multilayer coating on a substrate prior to photolithographic exposure, comprising:

• A contrast enhancing layer (BCEL) consisting of one of the proposed photosensitive coating materials, ie a photodegradable alkaline additive and / or a photolytic acid generator and a base polymer having no acid cleavable groups, the contrast enhancement layer being deposited on the substrate becomes; and
• - At least one photosensitive resist film, which is arranged on the contrast enhancement layer, so that the contrast enhancement layer (BCEL) contacts the photosensitive resist film on the paint bottom surface, that is arranged below the paint film.

Of the Paint film may include: another base polymer having an acid-sensitive group; and a photolytic acid generator for generating an acid when exposed to optical light, UV or X-rays, electrons, charged particles, ion projection lithography. The released Acid is designed to be the acid-sensitive group from the remaining polymer cleaves to the polarity of this Base polymer to change. A selective removal of changed Polymer sections with respect not changed Sections are thus made possible, for example, with the aid of a developer solution.

According to one In another aspect, a substrate is provided having a surface that through the multiple layer according to the above mentioned Aspect is formed. Process for the preparation of photosensitive Coating material and for exposing a semiconductor wafer using this material are also indicated in the appended claims.

The photosensitive coating material, as described in aspects and embodiments of This invention is also described as BCEL in this document (Bottom Contrast Enhancing Layer) or simply as a photosensitive Contrast enhancement layer (CEL) described. You strengthened the contrast during and after exposure of the paint deposited on the BCEL. In particular, the photosensitive coating (BCEL) is submerged deposited on the paint film, i. First, the BCEL is applied and subsequently the paint is deposited or spin coated, etc. It improves the signature (the acid concentration profile) an exposure in an area near the bottom or the bottom interface of the deposited paint film.

in the Contrary to known contrast enhancement layers, in general deposited on a varnish, the proposed "BCEL" features to that effect that they are referring to a developer solvent insoluble is. That is, deblocked polymers due to exposure Lacks can be removed. However, the base polymers of BCEL can not be unblocked since they are not acid-cleavable Have groups.

there It should be noted that quite solvent are present, in which the components of the photosensitive Coating such as the base polymer, the photolytic acid generator and / or the photo-decomposable alkaline additive is soluble to the deposition (For example spin-coating) on a wafer or photomask surface. These solvents are however with those solvents incompatible for the Development step, which is carried out with respect to the paint.

Even though therefore, the photosensitive coating material photoactive components such as photolytic acid generators and / or photodecomposable alkaline additives, have these components essentially no effect on the nature of the base polymer the bottom-side coating during or after the exposure.

Much more are either the photolytic acid generators and / or photo-decomposable alkaline additives or their photoreactive products released acids and / or decomposed non-alkaline compounds each designed so that they diffuse into the adjacent paint film above the BCEL. More specifically, they are designed to be close to the border Diffuse area at the bottom of the paint to there the acid concentration in exposed portions of the varnish or an alkali concentration in comparison to unexposed or less exposed areas to reduce. As a result, the chemical contrast between exposed and unexposed areas, especially in the area at the bottom of the paint strengthened.

As used herein the term "alkaline" Such a material is here taken, which only has a larger value than the _pKa acids within the adjacent coating. The effect of the invention occurs namely a under this condition.

Of the Expression "substrate" comprises a base body a specific material such as silicon, glass or quartz, etc., and continue one or more on the surface of this body deposited layers. For some - not all - this one described embodiments can the body also present as a monocrystalline substrate.

It is preferred to form both layers directly above one another, the is called, they are in direct contact with each other. In addition, often arise dark Side praise or dark SRAFs that are transferred to the varnish, near the areas at the bottom of the paint film due to absorption of light inside of the paint. The diffusion length of acidic and alkaline molecules is too small for the paint film to be completely penetrated. consequently is the use of the photosensitive contrast-enhancing Coating preferred as a floor covering below the paint film. In this case can the diffusing molecules easily reach the area at the bottom of the paint film, leaving it there so to speak to a "post-exposure" in places darker Side praise or darker SRAFs can come: the resulting acid concentration is as if the local dose would be subsequently increased upon exposure.

The Photosensitive coating comprises a photoactive component. This component serves to increase the concentration of alkaline additives reduce or neutralize within exposed areas. Two aspects that can also be combined relate to embodiments the photoactive component. In one embodiment, the photoactive Component a photolytic acid generator, in a further embodiment becomes the photoactive component by the alkaline additive itself delivered, which is then photo-decomposable.

The outdiffusion of the acid released in the case of photolytic acid generators occurs primarily during a post-exposure bake step. The photosensitive coating contacts the paint film, causing outdiffusion of the released acid during the baking step within exposed areas of the BCEL into the paint film caused. Consequently, the acid concentration therein is increased, which is not the case with unexposed or less exposed areas. As a result, the chemical contrast between exposed and unexposed or less exposed areas is enhanced.

at this embodiment, which relates to the aspect of photolytic acid generators, may optionally refinement can be accomplished by adding alkaline additives to the photosensitive coating.

The alkaline additives, also known as quenchers, diffuse from the coating in the adjacent paint and lead to a reduction or neutralization of possible acid concentrations in unexposed or less exposed areas of the paint. Meanwhile, it is due the simultaneously diffusing acids only a moderate Reduction in exposed areas.

In leads in every case the outdiffusion of alkaline additives to a neutralization or a quench of acids, the while an exposure in the paint film are generated. Due to the finite diffusion length the quenching occurs in an area near the contact surface the paint film and the photosensitive coating, that is in one near the interface Ground area of the paint film.

It is possible, too, the coating comprising photolytic acid generators, photo-decomposable to add alkaline additives. Here, the chemical contrast, that between exposed and unexposed or less exposed Areas is achieved the strongest.

at the alternative embodiment regarding photodecomposable alkaline additives becomes a reduction the alkali concentration in exposed areas of the coating achieved. A special but non-limiting example of a photodecomposable alkaline additive concerns triphenylsulfonium acetate. As a result adding a photodecomposable base the alkaline outdiffusion is in the above adjacent paint film inhibited or at least reduced in these areas.

One Effect of the invention is accordingly that the chemical Contrast in acid concentrations between exposed and unexposed areas in the paint. Another effect is that the level of acid concentration in a near-surface Bottom area of the lacquer relative to near the outer (upper) surface of the lacquer increased areas or adapted to this. Because the optical contrast with the contrast in the acid concentration correlated, the invention acts as if the optical contrast has been enhanced would be and as if the strong absorption reduces in the direction of the paint bottom would.

In another aspect, the BCEL is designed to function as a floor antireflective layer (BARC). Therein, the refractive indices of the BCEL are designed to be in the range between the index of the overlying varnish and the index of the underlying coating, so that the reflection at the area boundaries is reduced, as in conventional antireflection techniques, for example, with a refractive index n in FIG Near the paint (for example, n _(BCEL) = n _(paint) ± 0.2) and an absorption coefficient in the range of, for example, 0.5 to 2.0 microns ^-1 .

With respect to the base polymer and solvents, the photosensitive coating is not limited to the specific embodiments set forth herein, and those skilled in the art will readily recognize that similar materials can be used with substantially the same effect:
The photosensitive coating material to be arranged as a contrast enhancement layer may, according to one embodiment, comprise a base polymer based on an acrylic or vinyl polymer platform. Examples are polyethers, polyesters, polyurethanes, polysaccharide-attached dyes, polymer blends with additional styrenic monomers, etc. Light-absorbing dyes can be attached to the acrylic or vinyl polymers. They can also be designed so that they are chemically crosslinkable (cross-linkable).

alternative can novolak, cresol novolak, polyhydroxystyrene, etc. for the Base polymer of the photosensitive coating material and the BCEL according to embodiments be used.

crosslinkers can according to a embodiment be added, which are of the melamine or urea type. Besides, they are secondary or tertiary alcohols possible.

When a solvent can according to embodiments conventional paint solvents used, such as, for example, methoxypropyl acetate, ethyl lactate, Cyclohexanone, cyclopentanone, γ-butyrolactone, Propylene glycol monomethyl ether acetate (PGMEA), propylene glycol monomethyl ether (PGME) etc.

Other embodiments relate to the aspect of a photolytic acid generator (PAG). The PAG may comprise triphenylsulfonium or diphenyliodonium salts of strong sulfonic acids, which are also referred to as Crivello salts. For example, triphenylsulfonium nonafluorobutanesulfonate or diphenyliodinium p-toluenesulfonate can be used for the photolytic acid generator.

In an alternative embodiment, with respect to the PAG, N, O-sulfonic acid esters, "o-nitrobenzylic acids", diazonaphthoquinone sulfonates (DNQ), AsF ₆ or SbF ₆ can be used, wherein the N, O-sulfonic acid esters can be, for example, phthalimidotosylates or related sulfone nitrogen-bonded esters of phthalimides.

If a quencher or an alkaline additive is added to the PAG, which is not photodecomposable, the alkaline additive with a first pKa value greater than a second, of pKa delivered to the adjacent paint. The alkaline additive may be an inorganic base or alternatively an organic base such as being an amine. For example, the alkaline additive be provided by trialkylamines or trialcoholamines. More specifically, the alkaline additive may be trioctylamine or Include triethanolamines. The alkaline additive may continue Tetramethylammonium acetate, etc. It does not need to be mentioned that one in the field and while executing the rules like here enclosed experienced person also other suitable photo-decomposable alkaline Consider materials.

It it should be noted that - e.g. in terms of Tetramethylammonium acetate - the Expression "alkaline Additive ", which in considered as a relative quantity relative to such acids throughout this document should be, which generally contained in the adjacent paint are, even weak acids, for example, carbonic acids (For example, with the addition of carboxylate), acetic acids, salicylic acids, etc. may include.

One another important aspect of the photosensitive coating the combination of a thermo acid generator with the feature of photo-decomposable alkaline additive inside the same coating. The thermogenic generator is designed to that he is an acid releases when its temperature is raised above a threshold, especially during a heating step. For example, the thermal acid generator a benzylthiolanium or benzyldithiolane compound of sulfonic acid. In a particular embodiment is the thermo acid generator one of the following: Benzylthiolanium hexafluoropropanesulfonate or Benzyldithiolaniumhexafluorpropansulfonat.

Further Tasks and many of the associated benefits of embodiments The present invention can be with reference to the following more detailed Description of preferred embodiments better appreciate in conjunction with the accompanying drawings and understand. Characteristics that are substantially or functionally the same or similar are denoted by the same reference numerals.

1 shows an embodiment of a photosensitive coating serving as a contrast enhancement layer disposed as a BARC under a resist film on a substrate;

2 - 5 show a sequence of cross-sectional profiles through the in 1 shown photosensitive arrangement with respect to different process steps according to embodiments of the invention;

6 - 8th show, in one embodiment (bottom coating with PAG), the resulting profiles of base or acid concentration as a function of the x-coordinate corresponding to those in 2 - 4 shown cross-sectional profiles;

9 - 11 With respect to another embodiment (BCEL coating with photo-decomposable alkaline additive), the resulting profiles of base or acid concentration as a function of the x-coordinate correspond to those in FIG 2 - 4 shown cross-sectional profiles;

12 - 14 show a third and fourth embodiment with respect to coatings with PAG and a photo-decomposable alkaline additive, respectively, onto which critical line-column patterns with auxiliary structures (SRAF) are projected in an exposure.

1 show an embodiment of a photosensitive coating acting as one on a semiconductor wafer 8th trained bottom contrast enhancement layer (BCEL) is used. A layer 12 of a material to be patterned (such as an oxide, a nitride, a metal, polysilicon, etc.) to be etched on a substrate 10 deposited, which may be a monocrystalline silicon. The in 1 The cross section shown is shown purely schematically, and it is obvious that instead of the one layer 12 Also, a plurality of structural layers in the form of a stack and having a topography not shown in the figures can be embodied in a similar manner.

A photosensitive coating 16 gets on the layer 12 applied. In this embodiment, the photosensitive coating comprises 16 a crosslinkable vinyl or acrylic polymer with attached dye, for example a polyether platform, a PGMEA solvent, a photochem settable alkaline additive such as triphenylsulphonium acetate and a thermogenic acid generator such as benzylthiolanium hexafluoropropanesulfonate or benzyldithiolanium hexafluoropropanesulfonate. The chemical composition of the thermal acid generator can be provided as follows:

A paint film 14 gets on the soil layer 16 spun on. The paint film 14 includes any conventionally known type of paint material that may be novolac based, chemically reinforced, vinyl or acrylic based, and / or crosslinked, etc. The paint comprises a photolytic acid generator in addition to a base polymer.

The base polymer of the photosensitive coating 16 is characterized in that it does not comprise an acid-cleavable group - in contrast to the base polymer of the paint film 14 , It is further noted that the photosensitive coating 16 and the paint film 14 have a direct contact surface to the diffusion of molecules between the two layers 14 . 16 to facilitate.

The paint material includes a solvent such that it is not the coating 16 dissolves. The coating 16 has a thickness in the range 30-800 nm, while the paint film 14 has a thickness of 50 to 400 nm. A first pre-bake step (cure or pre-bake) is performed to dry the still semi-liquid paint material.

2 - 5 show a sequence of on the in 1 shown wafers 8th applied process steps. First, as in 2 shown an exposure of a paint area 32 in a lithographic projection apparatus using light having a wavelength of, for example, 193 nm. The pattern transferred from a photomask may refer to a dense and periodic via structure or alternatively insulated column, each surrounded by a larger opaque or semitransparent layer on the projected mask.

Because the paint film 14 is sufficiently transparent, is also an area 22 the underlying photosensitive coating 16 (ie the BCEL) exposed. Exposure results in conversion of the slightly alkaline acetate ions of the triphenylsulfonium acetate to an acetic acid. The acidity of the latter compound is referred to throughout this document as "non-alkaline and neutral," and it is clear that these terms are merely relative quality It is important that the base level of the initial alkaline additive be reduced to exposed areas due to photodegradation 22 the bottom-side coating 16 lost or at least reduced. Unexposed or less exposed areas 24 the coating 16 however, reveal an unchanged concentration of alkaline additives, which is reflected in 2 represented as "B +".

• – die numerische Apertur beträgt 0,85;
• – annulare Beleuchtung mit σ_inner = 0,55 und σ_inner = 0,85;
• – die Dicke von Lack plus Beschichtung beträgt 360 nm;
• – die Beschichtung 16 weist weiterhin BARC-Eigenschaften auf (Brechungsindex angepasst an optische Eigenschaften des Lacks); und
• – bester Fokus und beste Dosis sind als Belichtungsparameter des jeweiligen Projektionsapparates in dieser Ausführungsform ausgewählt.

9 - 11 show a sequence of plots of acid and alkali concentrations plotted against the x-coordinate with respect to exposed areas 22 . 32 in the paint or in the underlying BCEL coating 16 , This exposed area corresponds to a line having a (critical) width of, for example, 90 nm. Further exposure conditions are: line-column pattern formed on the photomask, each line and each slit having a width of 90 nm;

• The numerical aperture is 0.85;
• - Annular illumination with σ _inner = 0.55 and σ _inner = 0.85;
• - The thickness of paint plus coating is 360 nm;
• - the coating 16 also has BARC properties (refractive index adapted to optical properties of the paint); and
• - Best focus and best dose are selected as the exposure parameters of the respective projection apparatus in this embodiment.

9 - 11 correspond to the embodiment, with respect to 1 - 5 is illustrated. 9 indicates the situation after the exposure. Accordingly, an acid concentration becomes inside the paint film 14 increases, and the alkali or quencher concentration within the BCEL coating 16 is in exposed areas 22 . 32 lowered.

After exposure / projection, a post bake (PEB) is performed at temperatures in the range of 50 ° C-170 ° C. In a preferred embodiment, a range of 100 ° C-150 ° C is contemplated. The thermo acid generator releases an acid under these temperatures. Because the temperature is applied to the entire wafer, the acid concentration begins throughout the coating 16 to increase over the wafer. This situation is in 10 shown.

The use of a thermogenic acid generator as a precursor to the acid provides a particular advantage: the annealing step is necessary and can not be circumvented. However, it has been found that most photolytic acid genera gates or free acids are thermally decomposed at the respective temperatures. This could lead to a reduced storage time of a BCEL coating. In contrast, the thermo-acid generator of the present embodiment advantageously utilizes the features of the PEB annealing step.

Consequently, it comes in exposed areas 22 the coating 16 excessive acid concentration due to the thermally generated acids and due to the photo-generated acids by means of photo-decomposition. This excessive acidity is in 2 indicated by "A +".

Simultaneously with the thermal generation of the acids, diffusion of acidic and alkaline molecules is initiated within the annealing step, as in 3 shown. As a result of this diffusion, acids diffuse into exposed areas 32 the paint film 14 within a near-surface ground area. Similarly, alkaline additives diffuse in unexposed or less exposed areas 24 the coating 16 stay behind, in respective areas 34 the paint film. In any case, the respective local concentration of acids or bases is improved. In addition, the contrast in the base content or acidity between the areas decreases 32 . 34 near the bottom surface of the paint film 14 to.

This contrast is also in 11 shown in the 3 shown situation corresponds. It compares the effect of diffusion with an idealized case in which no diffusion is allowed.

An important effect is that dark side praise that within this near-surface area at the bottom of the paint film (shown by a dotted line in the figures) within the exposed area 34 are reduced, since the acid concentration is increased beyond a threshold value, which represents an effective removal in a subsequent development step, which in 4 is shown. The development can be carried out, for example, with a conventional TMAH developer. Note that the bottom-side coating 16 (BCEL) is not affected by the development because of the acids in the coating 16 no acid-sensitive groups can be cleaved off. 5 shows the result of a further etching step on the bottom coating and the underlying material layer 12 is carried out, wherein the developed paint film 14 ' is used as an etching mask.

Another embodiment is with respect to 6 - 8th shown. The exposure settings are similar to those described in detail above. The photosensitive coating 16 here comprises a photolytic acid generator instead of a photo-decomposable alkaline additive or instead of the thermo acid generator, as used in the first embodiment. Nevertheless, a photo-independent quencher of the photosensitive coating also becomes 16 added.

6 shows the profiles of acid or alkali concentration along the x-coordinate similarly 9 after performing an exposure. Due to the exposure, the PAG has acids within the exposure range 32 at the bottom of the varnish and inside the area 22 the photosensitive BCEL coating 16 released. 7 shows the situation after a neutralization of acids and quenchers within the layers 14 respectively. 16 during the baking step. At the same time, the bake step causes a net diffusion of acids in the paint, resulting in 8th is shown. The acid concentration in the paint bottom area that would occur without diffusion from the BCEL is given for comparison.

It It should be noted that the respective diffusion lengths and initial concentration of acids and the quencher can differ so that several vertical concentration profiles can be realized.

As a result of the net diffusion, a moderate quencher concentration B + in the unexposed area 34 of the paint film occur near the lower limit or contact surface of the paint film. In contrast, a significant acid concentration becomes A + in the exposed area 32 the paint film 14 achieved (see 3 which is also representative of this embodiment).

12 Figure 12 shows the result in terms of an embodiment applied to critical exposure conditions that would conventionally result in (not desired) transfer of assist features (SRAF) on the wafer if they are already present on the mask. It is not intended that these features be exposed on the wafer, but that the process window of the projection step will be improved. The structure to be transferred to the wafer is a dense line-and-column pattern. The target width on the wafer is 100 nm. The gap between the lines has a width of 240 nm. The SRAF structures have a width of 40 nm and are placed in the middle of the spaces between each two lines. The photosensitive coating has similar structural features to that of the first embodiment, that is, a photo-decomposable alkaline additive is implemented together with the thermogenic acid generator.

As can be seen from the dashed curve (acid concentration of the paint after PEB), In this embodiment, a significant improvement in chemical contrast is achieved. A comparison with the conventional case is in 13 shown. Acid contrast is enhanced from 27% to 68% under the simplified assumptions of this embodiment. The contrast enhancement reaches a factor of 2.5 in this embodiment.

14 shows a further embodiment in which the photosensitive coating 16 is provided with a PAG (for example, a Crivello salt such as triphenylsulfonium salts of sulfonic acids) and a photo-independent quencher (eg, trioctylamine, etc.). The contrast is still 50% in this embodiment, representing a contrast enhancement factor of almost 2.0 in the prior art.

10

substratum

12

layer on the substrate

14

paint film

16

Photosensitive Coating, BCEL

18

surface close Area in the lower part of the paint film, diffusion area

22

Illuminated Area in BCEL

24

unexposed Area in BCEL

32

Illuminated Area in paint film

34

unexposed Area in paint film

40

beam of light

50

etching

60 61

diffusion

Claims (52)

Photosensitive coating material for deposition underneath a photoresist film ( 14 ) for enhancing a contrast of a photolithographic exposure of the photoresist film ( 14 ), comprising: a base polymer which does not comprise acid-cleavable groups to be insoluble in a developer designed to remove exposed portions of the paint film; A solvent for applying the photosensitive coating material on a surface of a substrate; A photolytic acid generator which upon exposure to optical light, UV or X-radiation, electrons, charged particles, ion projection lithography liberates an acid, which acid can diffuse into the adjacent lacquer when applied to a coating ( 16 ) formed of the photosensitive coating material to coat one in exposed portions of the paint film ( 14 ) to strengthen formed acid concentration. A photosensitive coating material according to claim 1, further comprising: - an alkaline additive which is constituted, (a) in the adjacent paint film ( 14 ) which diffuses on the coating formed from the photosensitive coating material ( 16 ) is deposited to one in unexposed sections ( 34 ) to reduce or neutralize acid concentration formed therein, and / or (b) a concentration of the acid in unexposed portions ( 34 ) the coating formed from the photosensitive coating material ( 16 ) to reduce or neutralize. Photosensitive coating material according to claim 1, wherein the base polymer is an acrylic or vinyl polymer. Photosensitive coating material according to claim 3, wherein a light-absorbing dye attached to the base polymer is. Photosensitive coating material according to a the claims 3 or 4, wherein the base polymer is one of the group comprising includes: polyether, polyester, polyurethane, a polysaccharide-attached Dye styrenated with styrene monomers Polymer mixture. Photosensitive coating material according to claim 1, wherein the base polymer is one of the following: novolaks, cresol novolaks or polyhydroxystyrene. Photosensitive coating material according to claim 6, wherein a light-absorbing dye attached to the base polymer is. Photosensitive coating material according to claim 1, further with a crosslinker. Photosensitive coating material according to claim 8, wherein the crosslinker is of a melamine type or a urea type. Photosensitive coating material according to claim 8, wherein the crosslinker is a secondary or tertiary alcohol is. The photosensitive coating material of claim 1, wherein the photolytic acid generator comprises one of the following: Crivello salts, N, O-sulfonic acid esters, "o-nitrobenzylic acids", diazonaphthoquinone sulfonates (DNQ), AsF ₆ or SbF ₆ . Photosensitive coating material according to claim 11, wherein the Crivello salts are one of the following: triphenylsulfonium of sulphonic acids, Diphenyliodonium salts of sulfonic acids. Photosensitive coating material according to claim 11, wherein the N, O-sulfonic acid esters are phthalimidotosylates or related sulfone nitrogen-bonded esters of phthalimides. The photosensitive coating material of claim 2, wherein the alkaline additive is associated with a first pKa greater than one in the adjacent paint film (US Pat. 14 ) formed second pKa value. Photosensitive coating material according to claim 2, wherein the alkaline additive is an inorganic base. Photosensitive coating material according to claim 2, wherein the alkaline additive is an organic amine. Photosensitive coating material according to claim 16, wherein the alkaline additive is at least one of the following is trialkylamine or trialcoholamines. Photosensitive coating material according to claim 17, wherein the alkaline additive is a trioctylamine or a triethanolamine is. Photosensitive coating material additive a tetramethylammonium acetate. Photosensitive coating material according to claim 1, wherein the solvent one of the following is: Propylene glycol monomethyl ether (PGMEA), Ethyl lactate, cyclohexanone, γ-butyrolactone. Photosensitive coating material for deposition under a photoresist film ( 14 ) for enhancing a contrast of a photolithographic exposure of the paint film ( 14 ), comprising: a base polymer which does not comprise acid-cleavable groups to be insoluble in a developer designed to remove exposed portions of the paint film; A solvent for applying the photosensitive coating material on a surface of a substrate; An alkaline additive which is such that: (a) when exposed to optical light, UV or X-radiation, electrons, charged particles, ion projection lithography, is photo-degradable to a non-alkaline neutral compound; Coating ( 16 ) deposited adjacent paint film ( 14 ) diffused, the coating ( 16 ) is formed from the photosensitive coating material to cut in unexposed or less exposed from ( 34 ) of the paint film ( 14 ) reduced acid concentration. Photosensitive coating material according to claim 21, wherein the photo-decomposable alkaline additive is a chemical Compound is with a pKa value, which by means of exposure with optical light, UV or X-ray radiation, Electrons, charged particles, ion projection lithography increases. Photosensitive coating material according to claim 21, wherein the photo-decomposable alkaline additive triphenylsulfonium acetate includes. Photosensitive coating material according to claim 21, continue with an acid generator. Photosensitive coating material according to claim 24, the acid generator a photolytic acid generator is. The photosensitive coating material of claim 25, wherein the photolytic acid generator is adapted to release an acid upon exposure to optical light, UV or X-radiation, electrons, charged particles, ion projection lithography, wherein the acid is adapted to penetrate into the adjacent paint film ( 14 ) diffused on the coating ( 16 ) formed of the photosensitive coating material to one in exposed portions ( 32 ) of the lacquer to increase acid concentration. Photosensitive coating material according to claim 24, the acid generator a thermo acid generator which is designed so that it releases an acid when its temperature over a Threshold is raised, especially during a Ausheizschritts. Photosensitive coating material according to claim 27, wherein the thermo acid generator a Benzylthiolanium or benzyldithiolanium compound of sulfonic acids. Photosensitive coating material according to claim 27, wherein the thermo acid generator of a the following is benzylthiolanium hexafluoropropanesulfonate or Benzyldithiolaniumhexafluorpropansulfonat. Photosensitive coating material according to claim 21, wherein the base polymer is an acrylic or vinyl polymer. Photosensitive coating material according to claim 30, wherein the base polymer is a light-absorbing dye is attached. Photosensitive coating material according to one of claims 30 or 31, wherein the base polymer is one of the group comprising: polyether, polyester, polyurethane, a polysaccharide-attached dye, styrene monomer-added polymer blend. Photosensitive coating material according to claim 21, wherein the base polymer is one of the following: novolaks, cresol novolaks or polyhydroxystyrene. Photosensitive coating material according to claim 33, wherein the base polymer is a light-absorbing dye is attached. Photosensitive coating material according to claim 21, continue with a crosslinker. Photosensitive coating material according to claim 35, wherein the crosslinker of a melamine type or a urea type is. Photosensitive coating material according to claim 35, wherein the crosslinker is a secondary or tertiary alcohol is. Photosensitive coating material according to claim 21, the solvent one of the following is: propylene glycol monomethyl ether (PGMEA), Ethyl lactate, cyclohexanone, γ-butyrolactone. Multilayer coating disposed on a substrate prior to photolithographic exposure comprising: a contrast enhancing coating ( 16 ), which is formed from a photosensitive coating material according to one of claims 1 to 20, wherein the coating ( 16 ) on the substrate ( 10 ) or a further layer ( 12 ) is applied; and at least one photosensitive coating film ( 14 ) applied to the coating ( 16 ) is arranged so that the coating ( 16 ) the photosensitive coating film ( 14 ) contacted at its bottom-side interface. A multilayer coating according to claim 39, wherein the contrast enhancing coating ( 16 ) is a floor antireflective coating (BARC). Multilayer coating disposed on a substrate prior to photolithographic exposure comprising: a contrast enhancing coating ( 16 ), which is formed from a photosensitive coating material according to any one of claims 21 to 38, wherein the coating ( 16 ) on the substrate ( 10 ) or a further layer ( 12 ) is arranged; and at least one photosensitive coating film ( 14 ) applied to the coating ( 16 ) is arranged such that the coating ( 16 ) the photosensitive coating film ( 14 ) contacted at its bottom-side interface. A multilayer coating according to claim 41, wherein the contrast enhancing coating ( 16 ) is a floor antireflective coating (BARC). Substrate ( 10 ) having a surface passing through the substrate or on the substrate ( 12 ), comprising a surface-mounted multilayer coating according to any one of claims 39 to 42. Substrate ( 10 ) according to claim 43, which is a photomask. Substrate ( 10 ) according to claim 43, which is a semiconductor wafer. Substrate ( 10 ) according to claim 43, wherein the surface of an inorganic layer ( 12 ) formed on the substrate ( 10 ) and is arranged to be patterned in a subsequent etching step. A method for producing a photosensitive coating material for enhancing the contrast of a photolithographic exposure of a photosensitive resist film ( 14 ), wherein the photosensitive coating material on a surface of a substrate ( 10 ) or a layer ( 12 ) and below the photosensitive resist film, comprising the following steps: - providing the substrate ( 10 ) a photosensitive coating material comprising: (a) a base polymer which does not comprise acid-cleavable groups to be insoluble in a developer designed to remove exposed portions of the paint film; (b) a solvent for applying the photosensitive coating material on a surface of the substrate ( 10 ) or the layer ( 12 ); (c) a photolithographic acid generator designed to release an acid upon exposure to optical light, UV or X-radiation, electrons, charged particles, ion projection lithography, the acid being adapted to diffuse into the adjacent resist, deposited on the layer formed of the photosensitive coating material to enhance an acid concentration formed in exposed portions of the resist; Dissolving the base polymer, the photolytic acid generator and the alkaline additive in the Solvent. A method for producing a photosensitive coating material for enhancing the contrast of a photolithographic exposure of a photosensitive resist film ( 14 ), wherein the photosensitive coating material on a surface of a substrate ( 10 ) or a layer ( 12 ) at the bottom of the photosensitive resist film ( 14 ), comprising the following steps: - providing the substrate ( 10 ) and a photosensitive coating material comprising: (a) a base polymer which does not comprise acid-cleavable groups to be insoluble in a developer designed to have exposed portions ( 32 ) of the paint film ( 14 ) to remove; (b) a solvent for applying the photosensitive coating material on a surface of the substrate ( 10 ) or the layer ( 12 ) on the substrate ( 10 ); (c) an alkaline additive designed to: (i) photodecomposable upon exposure to optical light, UV or X-radiation, electrons, charged particles, ion projection lithography to a non-alkaline neutral compound; Coating ( 16 ), which is formed from the photosensitive coating material, deposited and thus adjacent paint film ( 14 ) diffused to one in unexposed or less exposed portions ( 34 ) of the paint film ( 14 ) to reduce the acid concentration formed, dissolving the base polymer and the photodecomposable alkaline additive in the solvent. A method of exposing a semiconductor wafer, comprising the steps of: applying a photosensitive coating material to a surface of the semiconductor wafer to form a contrast-enhancing coating ( 16 ) with respect to another paint film ( 14 ), the coating ( 16 ) comprising (a) a base polymer which does not comprise acid-cleavable groups, (b) an alkaline additive and (c) a photolytic acid generator; Applying a photosensitive lacquer to the contrast-enhancing layer in order to apply the lacquer film ( 14 ) whose contrast is to be enhanced after exposure; - exposure of the paint film ( 14 ) and the underlying coating ( 16 ) within in each case at least one section ( 22 . 32 ) with optical light, UV or X-radiation, electrons, charged particles, ion projection lithography, whereby a concentration of acids in the exposed portions ( 22 ) of the coating ( 16 ) is increased due to acids released from the first photolytic acid generators; Diffusing (a) released acids from the exposed sections ( 22 ) of the coating ( 16 ) in a near-surface area of the adjacent paint film ( 14 ) to an acid concentration in exposed sections ( 32 ) of the paint film ( 14 ) and (b) alkaline additives from unexposed or less exposed portions ( 24 ) of the coating ( 16 ) in the near-surface area of the paint film ( 14 ) to reduce the acid concentration in unexposed or less exposed sections ( 34 ) of the paint film ( 14 ) to reduce or neutralize, so that the contrast in the acid concentration between exposed ( 32 ) and unexposed ( 34 ) Sections is increased; Application of a developer solution to the paint film ( 14 ) to either the exposed ( 32 ) or the unexposed sections ( 34 ) to remove it. A method of exposing a semiconductor wafer, comprising the following steps: applying a photosensitive coating material to a surface of the semiconductor substrate to form a coating ( 16 ) with respect to another paint film ( 14 ), the coating ( 16 ) comprising: (a) a base polymer which does not comprise acid-cleavable groups, (b) a photo-decomposable alkaline additive, and (c) a thermogenic acid generator; Applying a photosensitive coating to the coating ( 16 ) to apply a paint film ( 14 ) to train; - applying a thermal annealing step to release acids in the coating by means of the thermogenic generator; - exposure of the paint film ( 14 ) and the underlying coating ( 16 ) within at least one section ( 22 . 32 ) with optical light, UV or X-radiation, electrons, charged particles, ion projection lithography, whereby a concentration of alkaline additives in the exposed sections ( 22 ) of the coating ( 16 ) is reduced to neutral compounds due to decomposition; Diffusing (a) the thermally released acids from exposed sections ( 22 ) of the coating near the surface of the adjacent paint film ( 14 ) to an acid concentration in the exposed portions ( 32 ) of the paint film ( 14 ) and (b) alkaline additives used in unexposed or less exposed portions ( 24 ), from the coating ( 16 ) in the near-surface area of the paint film ( 14 ) to reduce the acid concentration in unexposed or less exposed portions ( 34 ) of the paint film ( 14 ) to reduce or neutralize, so that the contrast in the acid concentration zwi the exposed ( 32 ) and unexposed ( 34 ) Sections in it is increased; Application of a developer solution to the paint film ( 14 ) to either exposed ( 32 ) or unexposed ( 34 ) To remove sections of it. A method according to any one of claims 49 or 50, wherein the step Diffusion of the alkaline additive or acids in the paint film with the aid of a baking step after the exposure carried out becomes. The method of claim 51, further comprising the step of etching the coating ( 16 ) using the paint film ( 14 ) as an etch mask after either exposure ( 32 ) or unexposed sections ( 34 ) have been removed.